/*
 *   This program is free software: you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation, either version 3 of the License, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

/*
 *    StringToNominal.java
 *    Copyright (C) 2002-2012 University of Waikato, Hamilton, New Zealand
 *
 */

package weka.filters.unsupervised.attribute;

import java.util.ArrayList;
import java.util.Enumeration;
import java.util.Vector;

import weka.core.Attribute;
import weka.core.Capabilities;
import weka.core.Capabilities.Capability;
import weka.core.Instance;
import weka.core.Instances;
import weka.core.Option;
import weka.core.OptionHandler;
import weka.core.Range;
import weka.core.UnsupportedAttributeTypeException;
import weka.core.Utils;
import weka.core.WeightedAttributesHandler;
import weka.core.WeightedInstancesHandler;
import weka.filters.Filter;
import weka.filters.UnsupervisedFilter;

/**
 * <!-- globalinfo-start --> Converts a range of string attributes (unspecified
 * number of values) to nominal (set number of values). You should ensure that
 * all string values that will appear are represented in the first batch of the
 * data.
 * <p/>
 * <!-- globalinfo-end -->
 * 
 * <!-- options-start --> Valid options are:
 * <p/>
 * 
 * <pre>
 * -R &lt;col&gt;
 *  Sets the range of attribute indices ("first" and "last" are valid values
 *  and ranges and lists can also be used) (default "last").
 * </pre>
 * 
 * <pre>
 * -V &lt;col&gt;
 *  Invert the range specified by -R.
 * </pre>
 * 
 * <!-- options-end -->
 * 
 * @author Len Trigg (len@reeltwo.com)
 * @version $Revision$
 */
public class StringToNominal extends Filter implements UnsupervisedFilter, OptionHandler, WeightedAttributesHandler, WeightedInstancesHandler {

    /** for serialization */
    private static final long serialVersionUID = 4864084427902797605L;

    /** The attribute's range indices setting. */
    private final Range m_AttIndices = new Range("last");

    /**
     * Returns a string describing this filter
     * 
     * @return a description of the filter suitable for displaying in the
     *         explorer/experimenter gui
     */
    public String globalInfo() {

        return "Converts a range of string attributes (unspecified number of values) to nominal " + "(set number of values). You should ensure that all string values that " + "will appear are represented in the first batch of the data.";
    }

    /**
     * Returns the Capabilities of this filter.
     * 
     * @return the capabilities of this object
     * @see Capabilities
     */
    @Override
    public Capabilities getCapabilities() {
        Capabilities result = super.getCapabilities();
        result.disableAll();

        // attributes
        result.enableAllAttributes();
        result.enable(Capability.MISSING_VALUES);

        // class
        result.enableAllClasses();
        result.enable(Capability.MISSING_CLASS_VALUES);
        result.enable(Capability.NO_CLASS);

        return result;
    }

    /**
     * Sets the format of the input instances.
     * 
     * @param instanceInfo an Instances object containing the input instance
     *                     structure (any instances contained in the object are
     *                     ignored - only the structure is required).
     * @return true if the outputFormat may be collected immediately.
     * @throws UnsupportedAttributeTypeException if the selected attribute a string
     *                                           attribute.
     * @throws Exception                         if the input format can't be set
     *                                           successfully.
     */
    @Override
    public boolean setInputFormat(Instances instanceInfo) throws Exception {

        super.setInputFormat(instanceInfo);
        m_AttIndices.setUpper(instanceInfo.numAttributes() - 1);
        return false;
    }

    /**
     * Input an instance for filtering. The instance is processed and made available
     * for output immediately.
     * 
     * @param instance the input instance.
     * @return true if the filtered instance may now be collected with output().
     * @throws IllegalStateException if no input structure has been defined.
     */
    @Override
    public boolean input(Instance instance) {

        if (getInputFormat() == null) {
            throw new IllegalStateException("No input instance format defined");
        }
        if (m_NewBatch) {
            resetQueue();
            m_NewBatch = false;
        }

        if (isOutputFormatDefined()) {
            Instance newInstance = (Instance) instance.copy();

            // make sure that we get the right indexes set for the converted
            // string attributes when operating on a second batch of instances
            for (int i = 0; i < newInstance.numAttributes(); i++) {
                if (newInstance.attribute(i).isString() && !newInstance.isMissing(i) && m_AttIndices.isInRange(i)) {
                    Attribute outAtt = outputFormatPeek().attribute(i);
                    String inVal = newInstance.stringValue(i);
                    int outIndex = outAtt.indexOfValue(inVal);
                    if (outIndex < 0) {
                        newInstance.setMissing(i);
                    } else {
                        newInstance.setValue(i, outIndex);
                    }
                }
            }
            push(newInstance, false); // No need to copy
            return true;
        }

        bufferInput(instance);
        return false;
    }

    /**
     * Signifies that this batch of input to the filter is finished. If the filter
     * requires all instances prior to filtering, output() may now be called to
     * retrieve the filtered instances.
     * 
     * @return true if there are instances pending output.
     * @throws IllegalStateException if no input structure has been defined.
     */
    @Override
    public boolean batchFinished() {

        if (getInputFormat() == null) {
            throw new IllegalStateException("No input instance format defined");
        }
        if (!isOutputFormatDefined()) {

            setOutputFormat();

            // Convert pending input instances
            for (int i = 0; i < getInputFormat().numInstances(); i++) {
                push((Instance) getInputFormat().instance(i).copy(), false); // No need to copy
            }
        }

        flushInput();
        m_NewBatch = true;
        return (numPendingOutput() != 0);
    }

    /**
     * Returns an enumeration describing the available options.
     * 
     * @return an enumeration of all the available options.
     */
    @Override
    public Enumeration<Option> listOptions() {

        Vector<Option> newVector = new Vector<Option>(1);

        newVector.addElement(new Option("\tSets which attributes to process (\"first\" and \"last\" are valid values " + "and ranges and lists can also be used) (default \"last\").", "R", 1, "-R <col>"));

        newVector.addElement(new Option("\tInvert the range specified by -R.", "V", 1, "-V <col>"));

        return newVector.elements();
    }

    /**
     * Parses a given list of options.
     * <p/>
     * 
     * <!-- options-start --> Valid options are:
     * <p/>
     * 
     * <pre>
     * -R &lt;col&gt;
     * Sets the range of attribute indices ("first" and "last" are valid values
     * and ranges and lists can also be used) (default "last").
     * </pre>
     * 
     * <pre>
     * -V &lt;col&gt;
     *  Invert the range specified by -R.
     * </pre>
     * 
     * <!-- options-end -->
     * 
     * @param options the list of options as an array of strings
     * @throws Exception if an option is not supported
     */
    @Override
    public void setOptions(String[] options) throws Exception {

        String attIndices = Utils.getOption('R', options);
        if (attIndices.length() != 0) {
            setAttributeRange(attIndices);
        } else {
            setAttributeRange("last");
        }

        String invertSelection = Utils.getOption('V', options);
        if (invertSelection.length() != 0) {
            m_AttIndices.setInvert(true);
        } else {
            m_AttIndices.setInvert(false);
        }

        if (getInputFormat() != null) {
            setInputFormat(getInputFormat());
        }

        Utils.checkForRemainingOptions(options);
    }

    /**
     * Gets the current settings of the filter.
     * 
     * @return an array of strings suitable for passing to setOptions
     */
    @Override
    public String[] getOptions() {

        Vector<String> options = new Vector<String>();

        options.add("-R");
        options.add("" + (getAttributeRange()));

        if (this.m_AttIndices.getInvert()) {
            options.add("-V");
        }

        return options.toArray(new String[0]);
    }

    /**
     * @return tip text for this property suitable for displaying in the
     *         explorer/experimenter gui
     */
    public String attributeRangeTipText() {

        return "Sets which attributes to process (\"first\" and \"last\" are valid values " + "and ranges and lists can also be used).";
    }

    /**
     * Get the range of indices of the attributes used.
     * 
     * @return the index of the attribute
     */
    public String getAttributeRange() {

        return m_AttIndices.getRanges();
    }

    /**
     * Sets range of indices of the attributes used.
     * 
     * @param rangeList the list of attribute indices
     */
    public void setAttributeRange(String rangeList) {

        m_AttIndices.setRanges(rangeList);
    }

    /**
     * Set the output format. Takes the current average class values and
     * m_InputFormat and calls setOutputFormat(Instances) appropriately.
     */
    private void setOutputFormat() {

        Instances newData;
        ArrayList<Attribute> newAtts;
        ArrayList<String> newVals;

        // Compute new attributes

        newAtts = new ArrayList<Attribute>(getInputFormat().numAttributes());
        for (int j = 0; j < getInputFormat().numAttributes(); j++) {
            Attribute att = getInputFormat().attribute(j);
            if (!m_AttIndices.isInRange(j) || !att.isString()) {

                // We don't have to copy the attribute because the
                // attribute index remains unchanged.
                newAtts.add(att);
            } else {

                // Compute list of attribute values
                newVals = new ArrayList<String>(att.numValues());
                for (int i = 0; i < att.numValues(); i++) {
                    newVals.add(att.value(i));
                }
                Attribute newAtt = new Attribute(att.name(), newVals);
                newAtt.setWeight(att.weight());
                newAtts.add(newAtt);
            }
        }

        // Construct new header
        newData = new Instances(getInputFormat().relationName(), newAtts, 0);
        newData.setClassIndex(getInputFormat().classIndex());
        setOutputFormat(newData);
    }

    /**
     * Main method for testing this class.
     * 
     * @param argv should contain arguments to the filter: use -h for help
     */
    public static void main(String[] argv) {
        runFilter(new StringToNominal(), argv);
    }
}
